iStock/Thinkstock(PEOTONE, Ill.) -- Heavy fog blanketing the area may be a factor in an interstate multi-vehicle pileup in Illinois. State Police say several vehicles were involved in the accident in the northbound lanes of Interstate 57 near Peotone.

Authorities diverted traffic around the scene of the pileup, where witnesses say vehicles appeared to be stranded as well.

"I don't know why they are all to the side," motorist Lindsey Bialek said. "I don't know if they were trying to see what was going on."

Bialek said visibility was so low in the area that drivers were forced to drive about 30 miles an hour "because you could barely see in front of you. We all had our hazards on." At the time she passed through, Bialek said "there were at least 20, 25 [cars in accidents]. It could have been more."